Planetary lander

ABSTRACT

A drag ring penetrometer combination of the type employed for determining the atmospheric and surface characteristics of planets, the drag ring aerodynamically stabilizing and decelerating the penetrometer during its planetary entry to thereby permit continuous transmission of communication during entry and to reduce the aerodynamic heating of the penetrometer, and also to thereby permit a desired amount of oriented penetration into the planet surface.

. United States Patent Primary Examiner-Milton Buchler Assistant Examiner-James E. Pittenger Att0meysPhillip L. De Arment and Gay Chin ABSTRACT: A drag ring penetrometer combination of the type employed for determining the atmospheric and surface characteristics of planets, the drag ring aerodynamically stabilizing and decelerating the penetrometer during its planetary entry to thereby permit continuous transmission of communication during entry and to reduce the aerodynamic heating of the penetrometer, and also to thereby permit a desired amount of oriented penetration into the planet surface.

[72] Inventor CarlosdeMoraes 1,838,035 12/1931 Littleton,Co1o. 2,398,794 4/1946 [21] AppLNo. 778,933 3,098,630 7/1963 [22] Filed Nov.26,1968 3,321,154 5/1967 [45] Patented Sept. 14,1971 3,339,404 9/1967 [73] Assignee Martin MariettaCorporation 3,368,480 2/1968 Baltimore, Md.

[54] PLANETARY LANDER 17 Claims, 6 Drawing Figs.

[52] U.S.C1 244/138, 102/4 [51] 1nt.Cl B64d1/00 [50] FieldotSearch ..244/1,138, 110, 113; 102/4; 244/324, 3.27

[56] References Cited UNITED STATES PATENTS 1,289,702 12/1918 Draper 102/4 15 ll 1 l l I '6 l8 20 w l .0

PATENIED SEPI 419m HGI INVENTOR CARLOS A. de MORAES BY W ATTORNEYS PLANETARY LANDER BACKGROUND OF THE INVENTION In todays continuous study of the various planets in the universe, particularly with regard to the possibility of supporting human life thereon, it is essential to have a prior knowledge of the planet's atmosphere and surface, In order to obtain reliable data concerning the nature of the planets atmosphere and surface, it has been proposed to employ a penetrometer which is carried to the desired planet by a suitable spacecraft. The penetrometer contains various measuring components such as atmospheric temperature, humidity, and pressure transducers; accelerometers, soil temperature and moisture sensors, and the like, whereby after being released from the spacecraft, the penetrometer is propelled toward the planet under study and while entering the planetary atmosphere, it measures and transmits various scientific measurements, related thereto, and when landing it penetrates the planets surface to thereby afford surface and subsurface geological, meteorological and astronomical explorations.

The aerodynamic design of the penetrometers employed for the above-noted planetary explorations has resulted in the use of a needle nose configuration which minimizes the inherent plasma interference to thereby permit continuous transmission of data as the penetrometer passes through the planetary atmosphere, However, it has been found that in penetrometers employing the needle nose configuration, the drag is low and the entry speed is high; thus, little time is available for obtaining and transmitting data during the interval of time between the entry of the penetrometer into the planetary atmosphere and its impact on the planets surface. Furthermore, aerodynamic stability is not obtained and an internal damper is required. Also impact velocity may be too high to permit equipment survival for transmitting data associated with the surface and subsurface characteristics.

In order to increase the entry time to thereby increase the time available for the obtaining and transmitting of data while the penetrometer passes through the planetary atmosphere, it has been proposed to employ a penetrometer having a blunt nose; that is, a spherical or conical configuration. While the blunt nose configuration increases the drag and reduces the entry speed of the penetrometer thereby increasing the time interval between entry and impact, it'has been found that the blunt nose configuration causes the development of a plasma sheath which results in a communication blackout during a significant portion of the entry time interval, the time after blackout being very short thus allowing very little time for the transmission of data before impact.

After considerable research and experimentation, the penetrometer of the present invention has been devised which comprises essentially a probe having a'needle nose configuration and a drag ring or any other similar protruding structure mounted on the tail portion thereof. The construction and arrangement of the penetrometer and associated drag-ring-type structure not only permits the continuous transmission of data as the penetrometer passes through the planetary atmosphere but also the entry speed is reduced to thereby increase the available time for the obtaining and transmission of data duringthe interval of time between entry and impact, and also permit an impact velocity which allows critical equipment to survive.

Furthermore, the drag ring structure employed on the penetrometer of the present invention is detachably secured thereto, whereby upon impact of the penetrometer with the planetary surface to be studied, the drag ring is released therefrom to avoid interference with the data collecting and transmitting components contained in the penetrometer.

IN THE DRAWINGS FIG. I is a sectional side elevational view of the penetrometer and associated drag ring;

FIG. 2 is a fragmentary sectional view showing a portion of the fractured drag ring after impact of the penetrometer with the surface of the planet to be studied;

FIG. 3 is a reduced end elevational view of the drag ring mounted on the tail portion of the penetrometer;

FIG. 4 is an enlarged, fragmentary view of a pivotal connection for securing a drag-ring-supporting strut to the penetrometer;

FIG. 5 is a view taken along line 5-5 of FIG. 4; and

FIG. 6 isan enlarged, fragmentary sectional view illustrating the construction of the drag ring.

Referring to the drawing, and more particularly to FIG. I, the penetrometer of the present invention comprises a housing containing conventional electrical and mechanical measuring and transmitting components, such as pressure transducer 2, mass spectrometer 3, impact accelerometer 4, battery 5, power switch 6, static storage unit, data encoder atmosphere ambient pressure transducer, and accelerometer triad 7; altitude-marking radar, hygrometer electronics, atmosphere temperature transducer, and soil temperature and moisture electronics 8; UHF transmitter, sequence clock, and anenometer electronics 9, camera 10 and anenometer II, the various components being supported within the housing by suitable shock mounts 12 and shock-absorbing material 13. The forward end portion of the housing is provided with a needle nose configuration 14 and the tail portion of the housing has a drag ring I5 mounted thereon.

As will be seen in FIGS. I and 6, the drag ring consists of a honeycomb core 16 enveloped by a fiberglass and ablator sheath l7 constructed and arranged to form a frustoconical annular member having weakened portions 18 forming shear lines, whereby the drag ring may break into sections upon impact of the penetrometer with the surface of the planet, to be described more fully hereinafter. The drag ring is supported on the tail portion of the penetrometer housing by a plurality of radial arms 19, each of which has its outer end portion rigidly connected to the outer peripheral portion of the ring, and its inner end portion connected to the penetrometer housing by means of a shear pin 20. A plurality of inclined struts 21 also support the drag ring on the penetrometer; the outer end portion of each strut being secured to and extending along the inclined surface of the ring, and the inner end portion of each strut being pivotally connected to the penetrometer housing as at 22. As will be seen in FIGS. 4 and 5, the pivotal connection 22 is provided with a ratchet portion 23 engaged by a pawl 24 secured to the penetrometer housing. Referring to FIG. 2, the positionof a portion of the drag ring after the impact of the penetrometer with the planetary surface is illustrated wherein it will be seen that upon impact, shear pins 20 break and the drag ring fractures along shear lines 18 to fon'n sections 15a. With the fracturing of the shear pins and ring, the struts 21 pivot downwardly, the struts being prevented from rebounding upwardly by means of the ratchet and pawl assembly 23, 24. The destruction of the drag ring now affords an unobstructed view of the planetary surface so that it may be photographed by the camera 10 mounted in the tail portion of the penetrometer housing.

It will be appreciated by those skilled in the art that the penetrometer housing, struts, arms and drag ring may be covered with an ablative material and it is desirable that the nose shock not intersect the ring during high heating conditions since, if it does, additional heat protection is required on the ring. In order to keep the nose shock from intersecting the ring during conditions of maximum heating, the angle y, viz; the angle between the longitudinal axis of the penetrometer and a line from the tip of the penetrometer nose to the leading edge of the drag ring, should be sufficiently large. Since the penetrometer is stable, the angle of attack during maximum heating willbe small therefore a value of angle 'y greater that 20 to 25 will be ample to satisfy this condition if the nose angle of the penetrometer is kept small, i.e. in the order of 9 to 12.

The construction and arrangement of the drag ring of the present invention also facilitates the continuous transmission of data during entry of the penetrometer into the planetary atmosphere since the strong shocks caused by the air at high Mach numbers are located around the ring, leaving the nose of the penetrometer essentially free of plasma interference.

With the drag ring located aft of the center of gravity of the penetrometer and having a ring angle B less that 90", preferably 60 to 70, the aerodynamic forces on the ring, as the angle of attack is varied, will be such so as to provide static and dynamic stability to the penetrometer. Furthermore, the ring of the present invention adds significantly to the drag of the penetrometer, resulting in low attainable values of the ballistic drag coefficient which, for high Mach numbers, can be approximated by the following equation:

c,,=2 sin fl l(Di/) wherein B is the ring angle, preferably 60 to 70; Di is the inside diameter of the ring, and D, the outside diameter of the ring; the inside diameter being approximately 0.5 to 0.7 of the outside diameter.

From the above description, it will be readily apparent that the drag ring of the present invention:

1. Significantly improves the stability of a planetary probe;

2. Provides a large amount of drag;

3. Minimizes plasma interference and permits continuous transmission of data during entry;

4. Minimizes the amount of ablative material required to protect the penetrometer from aerodynamic heating; and

5. Provides the penetrometer for any atmospheric density,

with a desired impact velocity which may be low enough to permit equipment survival.

After impacting the planet surface, the depth of penetration is dependent essentially upon the impact velocity, surface soil or rock composition, penetrometer total mass, nose shape or cone angle of penetrometer, and the diameter of the penetrometer. In some cases, the penetrometer diameter may vary to account for unknown surface soil variation ranges. Both analytical derivations along with comparisons of test data have led to the penetration formula given below:

where,

x, total displacement or depth of penetration in ft.

m mass of penetrometer at impact in (lb. sec. )/ft.

2 impact velocity in ft./sec.

A projected penetrometer cross-sectional area in in.

Uy'p effective soil yield strength in lb./in. for sand a'y'p =2,000 p.s.i., for rock 'y'p=l(),O00 p.s.i.

C= damping factor in lb. see/ft.

C D nose cone drag coefiicient depending on nose cone angle. Coefficient varies from 0.6 to 1.2.

From the above displacement calculation, peak 3 loads applied to equipment inside the penetrometer may be deter mined from known physics concepts.

lclaim:

l. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a planet, the nose angle of the penetrometer being inthe order of 9 to 12, a frustoconical annular member having a ring angle in the order of 60 to 70 providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said annular member on said shell, so that the angle between the longitudinal axis of the penetrometer and a line from the tip of the penetrometer nose to the leading edge of the annular member is greater than thereby providing a predetermined orientation of said drag surface relative to said penetrometer.

2. A lander as defined in claim 1, wherein the frustoconical annular member is constructed of a honeycomb core enveloped within a heat-protective sheath.

3. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a pianet, means providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, a plurality of arms extending between the shell and the drag surface, one end of each arm being connected to the drag surface, and the opposite end of each arm being connected to the penetrometer to provide a predetermined orientation of said drag surface relative to said penetrometer, and a shear pin detachably connecting said opposite end of each are to the penetrometer, whereby upon impact of the penetrometer with the surface of the planet to be studied the drag surface is permitted to move relative to said shell so as not to interfere with the data collecting and transmitting components contained in the shell.

4. A lander as defined in claim 3, wherein a plurality of struts extend between the penetrometer and the drag surface, one end of each strut being connected to the drag surface, and pivot means connecting the opposite end of the strut to the penetrometer, whereby when the shear pins break, the struts pivot the drag surface to an inoperative position away from the penetrometer.

5. A lander as defined in claim 4, wherein detent means are operatively connected to the pivot means to hold the struts and associated drag surface in the inoperative position.

6. A lander as defined in claim 3, wherein the drag surface includes a ring having a weakened portion forming shear lines whereby upon impact of the penetrometer with the surface of the planet the drag ring fractures into sections.

7. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a planet, means providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said drag surface on said shell to provide a predetermined orientation of said drag surface relative to said penetrometer, the diameter and nose of said shell being configured geometrically so that for a given impact velocity and total mass of the lander, the depth of penetration may be determined for various types of planet surface materials by the following relationship where,

X total displacement or depth of penetration in ft.

M= mass of penetrometer at impact in (lb. sec. )/ft.

jc impact velocity in ft./sec.

A projected penetrometer cross-sectional area in in.

a'y-p effective soil yield strength in lb./in.

for sand y'p=2,000 p.s.i.

. rock y-p==l0,000 p.s.i.

C damping factor in lb. sec./ft.

C nose cone drag coefficient depending on nose cone angle. Coefficient varies from 0.6 to 1.2.

8. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmosphere and surface characteristics of planets and configured to penetrate the surface of a planet, a continuous ring surrounding said penetrometer providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said drag surface on said shell to provide a predetermined orientation of said drag surface relative to said penetrometer, said ring having a weakened portion forming shear lines, whereby upon impact of the penetrometer with the surface of the planet the ring fractures into sections, thereby preventing the ring from interfering with the data collecting and transmitting components contained in the shell.

9. A planetary lander as defined in claim 8, wherein the drag surface comprises a frustoconical annular member.

10. A planetary lander as defined in claim 9, wherein the frustoconical annular member is constructed of a honeycomb core enveloped within a heat-protective sheath.

1]. A planetary lander as defined in claim 9 wherein the ring angle of the annular member is in the order of 60 to 70, the nose angle of the penetrometer is in the order of 9 to 12, and the angle between the longitudinal axis of the penetrome- W ter and a line from the tip of the penetrometer nose to the leading edge of the drag ring is greater than 12. A planetary lander as defined in claim 9 wherein said frustoconical ring forms an angle with the longitudinal axis of said penetrometer of from 60 to 70.

13. A planetary lander as defined in claim 8 wherein said means mounting said drag surface includes means detachably connecting the drag surface to the penetrometer and responsive upon impact of the penetrometer with the surface of the planet to be studied to permit the drag surface to move relative to said shell.

14. A planetary lander as defined in claim 13 wherein said means for detachably connecting the drag surface to the penetrometer shell comprises a plurality of arms extending between the shell and the drag surface, one end of each arm being connected to the drag surface, and the opposite end of each arm being connected to the penetrometer, and a shear pin connecting said opposite end of each arm to the penetrometer.

15. A planetary lander as defined in claim 14 wherein said means for detachably connecting the drag surface to said shell further includes a plurality of struts extending between the penetrometer and the drag surface, one end of each strut being connected to the drag surface, and pivot means connecting the opposite end of the strut to the penetrometer, whereby when the sheer pins break, the struts pivot the drag surface to an inoperative position away from the penetrometer.

16. A planetary lander as defined in claim 15 wherein detent means are operatively connected to the pivot means to hold the struts and associated drag surface in the inoperative position.

17. A planetary lander as defined in claim 8 wherein the diameter and nose of said shell are configured geometrically so that for a given impact velocity and total mass of the lander, the depth of penetration may be determined for various types of planet surface materials by the following relationship Mir,

(AC ay-p+ OX.) 3 V- 

1. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a planet, the nose angle of the penetrometer being in the order of 9* to 12*, a frustoconical annular member having a ring angle in the order of 60* to 70* providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said annular member on said shell, so that the angle between the longitudinal axis of the penetrometer and a line from the tip of the penetrometer nose to the leading edge of the annular member is greater than 20*, thereby providing a predetermined orientation of said drag surface relative to said penetrometer.
 2. A lander as defined in claim 1, wherein the frustoconical annular member is constructed of a honeycomb core enveloped within a heat-protective sheath.
 3. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a planet, means providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, a plurality of arms extending between the shell and the drag surface, one end of each arm being connected to the drag surface, and the opposite end of each arm being connected to the penetrometer to provide a predetermined orientation of said drag surface relative to said penetrometer, and a shear pin detachably connecting said opposite end of each are to the penetrometer, whereby upon impact of the penetrometer with the surface of the planet to be studied the drag surface is permitted to move relative to said shell so as not to interfere with the data collecting and transmitting components contained in the shell.
 4. A lander as defined in claim 3, wherein a plurality of struts extend between the penetrometer and the drag surface, one end of each strut being connected to the drag surface, and pivot means connecting the opposite end of the strut to the penetrometer, whereby when the shear pins break, the struts pivot the drag surface to an inoperative position away from the penetrometer.
 5. A lander as defined in claim 4, wherein detent means are operatively connected to the pivot means to hold the struts and associated drag surface in the inoperative position.
 6. A lander as defined in claim 3, wherein the drag surface includes a ring having a weakened portion forming shear lines whereby upon impact of the penetrometer with the surface of the planet the drag ring fractures into sections.
 7. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmospheric and surface characteristics of planets and configured to penetrate the surface of a planet, means providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said drag surface on said shell to provide a predetermined orientation of said drag surface relative to said penetrometer, the diameter and nose of said shell being configured geometrically so that for a given impact velocity and total mass of the lander, the depth of penetration may be determined for various types of planet surface materials by the following relationship where, X1 total displacement or depth of penetration in ft. M mass of penetrometer at impact in (lb. sec.2)/ft. X0 impact velocity in ft./sec. A projected penetrometer cross-sectional area in in.2 y.p effective soil yield strength in lb./in.2 for sand y.p 2,000 p.s.i. rock y.p 10,000 p.s.i. C damping factor in lb. sec./ft. CD nose cone drag coefficient depending on nose cone angle. Coefficient varies from 0.6 to 1.2.
 8. A planetary lander comprising a penetrometer having an elongated aerodynamic shell adapted to house instruments for measuring the atmosphere and surface characteristics of planets and configured to penetrate the surface of a planet, a continuous ring surrounding said penetrometer providing a drag surface configured to stabilize and control the deceleration and velocity of said lander to permit the instruments to function, and means mounting said drag surface on said shell to provide a predetermined orientation of said drag surface relative to said penetrometer, said ring having a weakened portion forming shear lines, whereby upon impact of the penetrometer with the surface of the planet the ring fractures into sections, thereby preventing the ring from interfering with the data collecting and transmitting components contained in the shell.
 9. A planetary lander as defined in claim 8, wherein the drag surface comprises a frustoconical annular member.
 10. A planetary lander as defined in claim 9, wherein the frustoconical annular member is constructed of a honeycomb core enveloped within a heat-protective sheath.
 11. A planetary lander as defined in claim 9 wherein the ring angle of the annular member is in the order of 60* to 70*, the nose angle of the penetrometer is in the order of 9* to 12*, and the angle between the longitudinal axis of the penetrometer and a line from the tip of the penetrometer nose to the leading edge of the drag ring is greater than 20*.
 12. A planetary lander as defined in claim 9 wherein said frustoconical ring forms an angle with the longitudinal axis of said penetrometer of from 60* to 70*.
 13. A planetary lander as defined in claim 8 wherein said means mounting said drag surface includes means detachably connecting the drag surface to the penetrometer and responsive upon impact of the penetrometer with the surface of the planet to be studied to permit the drag surface to move relative to said shell.
 14. A planetary lander as defined in claim 13 wherein said means for detachably connecting the drag surface to the penetrometer shell comprises a plurality of arms extending between the shell and the drag surface, one end of each arm being connected to the drag surface, and the opposite end of each arm being connected to the penetrometer, and a shear pin connecting said opposite end of each arm to the penetrometer.
 15. A planetary lander as defined in claim 14 wherein said means for detachably connecting the drag surface to said shell further includes a plurality of struts extending between the penetrometer and the drag surface, one end of each strut being connected to the drag surface, and pivot means connecting the opposite end of the strut to the penetrometer, whereby when the sheer pins break, the struts pivot the drag surface to an inoperative position away from the penetrometer.
 16. A planetary lander as defined in claim 15 wherein detent means are operatively connected to the pivot means to hold the struts and associated drag surface in the inoperative position.
 17. A planetary lander as defined in claim 8 wherein the diameter anD nose of said shell are configured geometrically so that for a given impact velocity and total mass of the lander, the depth of penetration may be determined for various types of planet surface materials by the following relationship where, X1 total displacement or depth of penetration in ft. M mass of penetrometer at impact in (lb. sec.2)/ft. X0 impact velocity in ft./sec. A projected penetrometer cross-sectional area in in.2 y.p effective soil yield strength in lb./in.2 for sand y.p 2,000 p.s.i. for rock y.p 10,000 p.s.i. C damping factor in lb. sec./ft. C D nose cone drag coefficient depending on nose cone angle. Coefficient varies from 0.6 to 1.2. 